Investigating the use of netting structures as conditions suitable for off-season production of Moringa oleifera in South Africa

Abstract

Moringa oleifera, part of the Moringaceae family, is a subtropical plant renowned for its medicinal properties. Its leaves are often used as leafy vegetables or as primary ingredients in green smoothies. However, Moringa oleifera is highly sensitive to cold temperatures, which can severely hinder its growth and yield. The enhancement and assessment of growth, yield, and phytochemical composition of Moringa oleifera using Coolaroo frost cloth and a 40% shade net has not been previously documented. The aim of this study was to generate scientific information regarding the effects of the application of a white Coolaroo frost cloth and a white 40% shade nets with closed sides, top cover, closed sides and top, to protect Moringa oleifera during the winter season. The objectives of this study were, (1) to investigate the effect of a 40% shade net and Coolaroo Frost Cloth, with closed sides, top cover, closed sides and top, on the growth and yield attributes, and (2) phytochemical profiling of Moringa oleifera during winter. Following a randomized complete block design (RCBD), Moringa oleifera seedlings were transplanted onto plots covered with 40% shade net and established Coolaroo frost cloth with closed sides, top cover, and closed top sides. This process was carried out for 120 days, with three replications and six plants per replicate. Data were subjected to statistical analysis using GenStat 18th version statistical package (VSN International, Hempstead, UK). Mean separation for significant (p≤ 0.05) treatments were achieved using Tukey’s Honestly Significant Difference (HSD). The growth parameters, including plant height, stem diameter, and root length, were measured weekly until the experiment was completed. Yield parameters including plant biomass and number of leaves were recorded at harvest. After collection, the leaves, roots, and twigs were analyzed for their phytochemical composition. The growth and yield parameters of Moringa oleifera were significantly influenced (p≤ 0.05) by the Coolaroo frost cloth and the 40% shade net. At termination (120 days after transplanting), the Coolaroo frost cloth with closed sides and top had significantly increased the stem diameter, plant height, biomass production, root length and number of leaves. Untargeted metabolite profiling of the leaves, twigs, and roots was conducted using UPLC-MS to evaluate the effects of shading on secondary metabolite production, including phenolic compounds, flavonoids, and glycosides. Chemometric analysis of the UPLC-MS data revealed distinct effects of shading on different plant tissues. While the root metabolites showed no significant variation across shading treatments, the twigs and leaves exhibited pronounced differences. Twigs grown under 40% shade net and Coolaroo frost cloth with closed sides retained higher concentrations of key flavonoids such as quercetin 3-galactoside, rutin, and astragalin 7-rhamnoside. The leaves formed distinct clusters based on metabolite composition, with shading structures, especially the 40% shade net with closed top and sides, enhancing the accumulation of important phytochemicals like quecetrin and kaempferol derivatives. Overall, the study concludes that the use of Coolaroo frost cloth and shade nets provides a practical and cost-effective method for protecting Moringa oleifera from cold stress. These shading techniques not only improve plant growth and biomass yield but also enhance the phytochemical content, making the plant more valuable nutritionally and medicinally. The findings offer a sustainable solution for year-round Moringa cultivation in cold-prone regions, contributing to food security and agricultural sustainability.